The development of advanced composite materials has enabled the development of tanks and pressure vessels which are of lightweight and which have very thin walls. It will be appreciated that for aerospace applications, weight is a key parameter. More specifically, weight conservation is extremely important in such aerospace applications because the lighter the tank or pressure vessel, the more weight that can be allotted to the vehicle payload. Stated differently, cost is a barrier for commercial space applications, and every pound saved in the weight of a vehicle tank or pressure vessel can translate to a corresponding one pound increase in payload. The weight problem has been addressed through the use of high performance materials.
However, a challenge presented by such new high performance materials is the low impact damage tolerance thereof.
Exploring the latter point in more detail, high performance, filament wound composite pressure vessels, such as are used in solid propellant propulsion, spacecraft energy storage systems, and other similar demanding applications, have always been susceptible to damage from low velocity impact in both operational and non-operational environments. Concrete examples of this include a dropped wrench during the fabrication or assembly of the pressure vessel or the system with which the vessel is integrated, and an accidental “nudge” from a forklift or other of the innumerable tooling devices involved in the fabrication and assembly operations. It is noted that these things may or may not degrade the capability of the pressure vessel and a particularly worrisome problem is that these impacts, and the damage therefrom, may not be detectable. Thus, the need exists for a way to improve the capability of these pressure vessels to withstand such potentially degrading impacts, particularly if this can be done with little or no appreciable degradation in pressure vessel performance and without any increase in weight.